The Possible Pollen Cone of the Late Triassic Conifer Heidiphyllum/Telemachus (Voltziales) from Antarctica
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KU ScholarWorks | http://kuscholarworks.ku.edu Please share your stories about how Open Access to this article benefits you. The Possible Pollen Cone of the Late Triassic Conifer Heidiphyllum/ Telemachus (Voltziales) From Antarctica by Benjamin Bomfleur, Rudolph Serbet, Edith L. Taylor, and Thomas N. Taylor 2011 This is the published version of the article, made available with the permission of the publisher. The original published version can be found at the link below. Bomfleur, B., Serbet, R., Taylor, E., and Taylor, N. 2011. The Possible Pollen Cone of the Late Triassic Conifer Heidiphyllum/Telemachus (Voltziales) From Antarctica. Antarctic Science 23(4): 379-385. Published version: http://dx.doi.org/10.1017/S0954102011000241 Terms of Use: http://www2.ku.edu/~scholar/docs/license.shtml This work has been made available by the University of Kansas Libraries’ Office of Scholarly Communication and Copyright. Antarctic Science 23(4), 379–385 (2011) & Antarctic Science Ltd 2011 doi:10.1017/S0954102011000241 The possible pollen cone of the Late Triassic conifer Heidiphyllum/Telemachus (Voltziales) from Antarctica BENJAMIN BOMFLEUR, RUDOLPH SERBET, EDITH L. TAYLOR and THOMAS N. TAYLOR Division of Paleobotany at the Department of Ecology and Evolutionary Biology, and Natural History Museum and Biodiversity Institute, University of Kansas, Lawrence, KS 66045, USA bbomfl[email protected] Abstract: Fossil leaves of the Voltziales, an ancestral group of conifers, rank among the most common plant fossils in the Triassic of Gondwana. Even though the foliage taxon Heidiphyllum has been known for more than 150 years, our knowledge of the reproductive organs of these conifers still remains very incomplete. Seed cones assigned to Telemachus have become increasingly well understood in recent decades, but the pollen cones belonging to these Mesozoic conifers are rare. In this contribution we describe the first compression material of a voltzialean pollen cone from Upper Triassic strata of the Transantarctic Mountains. The cone can be assigned to Switzianthus Anderson & Anderson, a genus that was previously assumed to belong to an enigmatic group of pteridosperms from the Triassic Molteno Formation of South Africa. The similarities of cuticle and pollen morphology, together with co-occurrence at all known localities, indicate that Switzianthus most probably represents the pollen organ of the ubiquitous Heidiphyllum/Telemachus plant. Received 9 December 2010, accepted 23 February 2011, first published online 5 April 2011 Key words: coniferophytes, Gondwana, in situ pollen, Switzianthus, systematic palaeobotany, Transantarctic Mountains Introduction (Anderson 1978, Retallack 1981, Yao et al. 1993, Axsmith et al. 1998, Nielsen 2005, Escapa et al.2010).Further The Voltziales encompasses a diverse array of extinct evidence for Triassic transitional conifers from the Southern conifers that are believed to be transitional between the Hemisphere has come from permineralized deposits of Palaeozoic conifers and the modern Coniferales (e.g. Florin the central Transantarctic Mountains, which have yielded 1938–45, Rothwell et al. 2005, Taylor et al. 2009). The various anatomically preserved conifer organs, including majority of voltzialean taxa have been described from the stems and leaves of Notophytum krauselii Meyer-Berthaud upper Palaeozoic (e.g. Rothwell et al. 2005). There are, & Taylor (Meyer-Berthaud & Taylor 1991, Axsmith et al. however, fossils of this ancient conifer group that occur in 1998), seed cones of Parasciadopitys aequata Yao, Taylor deposits as young as the Early Jurassic (Taylor et al. 2009), & Taylor (Yao et al. 1997), and the pollen cone Leastrobus or possibly even Early Cretaceous (Miller 1977). fallae Hermsen, Taylor & Taylor (Hermsen et al. 2007). The Several Northern Hemisphere representatives of Mesozoic affinities and interrelationships of these fossils continue to voltzialean conifers have been intensely studied and are remain largely obscure. At least some of these morphotaxa, known in remarkable detail (e.g. Grauvogel-Stamm 1978). however, are regarded as being the permineralized By contrast, knowledge about the Gondwanan Voltziales has equivalents of the compression taxa Heidiphyllum and remained very incomplete. This is remarkable, because Telemachus (e.g. Axsmith et al. 1998, Escapa et al.2010, voltzialean conifer leaves have been described from the Schwendemann et al.2010). Gondwanan Triassic since the first half of the 19th century Even though voltzialean foliage and seed cones are (e.g. Morris 1845, Feistmantel 1889). These leaves have common elements in Gondwanan Triassic floras and have initially been assigned to a variety of morphogenera, (in part) been known for more than 150 years, information including Zeugophyllites Brongniart, Podozamites Braun, on the corresponding pollen cones has remained very Phoenicopsis Heer, Desmiophyllum Lesquereux, and limited. This may be due to the small size and ephemeral Noeggerathiopsis Feistmantel, but the vast majority were nature of these pollen cones (Rothwell & Mapes 2001, later merged into a single species Heidiphyllum elongatum Hermsen et al. 2007). In this contribution we present the (Morris) Retallack (Retallack 1981). Heidiphyllum is first record of voltzialean pollen cone compressions from currently recognized as the most widespread conifer leaf the Triassic of Antarctica. The specimens are assigned to in the Triassic of the Southern Hemisphere. It is frequently Switzianthus Anderson & Anderson, a morphogenus that found together with the supposedly affiliated seed was previously thought to belong to an enigmatic group of cone Telemachus Escapa, Decombeix, Taylor & Taylor pteridosperms from the Molteno Formation of South Africa 379 http://journals.cambridge.org Downloaded: 19 May 2014 IP address: 129.237.46.100 380 BENJAMIN BOMFLEUR et al. Fig. 2. Voltzialean foliage and seed cone from the Upper Triassic of the Allan Hills, south Victoria Land, East Antarctica. Scale bars 5 1 cm. a. Heidiphyllum elongatum (Morris) Retallack. T11-582a. b. Telemachus antarcticus Escapa, Decombeix, Taylor & Taylor. T11-411. Fig. 1. Locality map showing the fossil sites in south Victoria Land and the central Transantarctic Mountains, East Antarctica. Light grey tones indicate areas of rock outcrop. (Level 14, Profile 2 in Barrett 1969) with intercalated coaly layers and thin sheets of light-grey, very fine-grained (Anderson & Anderson 2003). By contrast, the similarities sandstone. The Falla Formation is interpreted as deposits in cuticle and pollen morphology, together with the co- of a low-sinuosity braided-stream system with a high occurrence at all known localities, lead us to the conclusion proportion of lacustrine and paludal overbank fines (e.g. that Switzianthus probably represents the pollen cone of the Barrett et al. 1986). A single additional specimen comes ubiquitous Heidiphyllum/Telemachus plant. from Member C of the Lashly Formation in the Allan Hills, south Victoria Land (Fig. 1). At both sites, the specimens co-occur with abundant Heidiphyllum leaves (Fig. 2a) Material and methods and Telemachus seed cones (Fig. 2b). The age of the Most specimens were collected from the type section plant-bearing horizons is considered to be Carnian or of the Falla Formation on the northern flank of the western Norian (early or middle Late Triassic) based on microfloras ridge of Mount Falla (Queen Alexandra Range, central (Kyle & Schopf 1982, Farabee et al. 1989). Transantarctic Mountains; 84822'S, 164855'E) (Fig. 1). Hand specimens were photographed with a Nikon D100 Plant fossils occur within a 16 m thick mudstone interval digital camera. Macroimages were taken with a Leica DC500 Fig. 3. Gross morphology, cuticle features, and in situ pollen of the voltzialean pollen cone Switzianthus sp. from the Upper Triassic of the Transantarctic Mountains. a. Intact pollen cone. Note that the spiny aspect of some sporophyll apices along the cone margin is due to individual superpositioned sporophylls being cross-sectioned. Mount Falla, T7-185a. Scale bar 5 5 mm. b. Counterpart of the same specimen. T7-185b. Scale bar 5 5 mm. c. Partially disintegrated pollen cone. Mount Falla, T7-172b. Scale bar 5 5 mm. d. Comparatively intact pollen cone. Allan Hills, T8-229b. Scale bar 5 5 mm. e&f.Details of individual ovate distal microsporophyll laminae with a slightly displaced central pedicel scar, a surrounding rugose area, and a distal portion with fine radiating striations. Scale bar 5 1 mm. g. Cuticle of the presumably outer (i.e. abaxial) surface of the distal microsporophyll lamina from a partially disintegrated pollen cone from Mount Falla (T5-111), showing the outlines of more or less longitudinally aligned, elongated rectangular to polygonal cells. Slide #24033. Scale bar 5 50 mm. h. Large cluster of Alisporites Daugherty type pollen grains isolated from a partially disintegrated cone from Mount Falla (T5-111). Slide #24034. Scale bar 5 100 mm. i–k. Individual pollen grains in polar (i & j) and lateral (k) view. Slides #24033 (j & k) and #24037 (i). Scale bars 5 25 mm. http://journals.cambridge.org Downloaded: 19 May 2014 IP address: 129.237.46.100 A TRIASSIC POLLEN CONE FROM ANTARCTICA 381 http://journals.cambridge.org Downloaded: 19 May 2014 IP address: 129.237.46.100 382 BENJAMIN BOMFLEUR et al. digital camera mounted on a Leica MZ16 stereo dissecting the entire grain; cappa generally thickened, with smooth or microscope. Cuticle and in situ pollen samples were freed finely reticulated to rugose surface; distal surface